STMicroelectronics STM1818SWX7F

Overview

STM1818SWX7F from STMicroelectronics is a low-power, open-drain active-low reset supervisor IC with manual reset detect, designed for 3.3 V/3.0 V microcontroller power monitoring. It features a factory-trimmed 4.37 V reset threshold (±2.5% accuracy), 100 ms minimum reset pulse width, 4 µA typical supply current, and guaranteed operation down to VCC = 1.0 V over –40 °C to +105 °C. Used in portable embedded systems requiring reliable brownout protection and push-button reset initiation.

For engineers reviewing the STM1818SWX7F datasheet, STM1818SWX7F pinout, STM1818SWX7F application, or STM1818SWX7F equivalent, this page delivers verified technical context, SOT23-3 package mapping, manual reset debounce timing (1.5 µs detection), internal 5.5 kΩ pull-up, and direct MCU interface compatibility without external components.

Technical Context

The STM1818SWX7F implements a precision voltage comparator with factory-trimmed 4.37 V threshold and ±2.5% accuracy across –40 °C to +105 °C, coupled to a reset timeout generator delivering ≥100 ms assertion after VCC recovery or MR trigger release. Its bidirectional RST pin supports both power-fail reset and debounced manual reset via 1.5 µs minimum low-pulse detection.

It uses an open-drain output with integrated 5.5 kΩ pull-up to VCC, enabling direct connection to bidirectional MCU reset pins without external components. The device maintains valid logic state down to VCC = 1.0 V and rejects transients ≤20 µs at 100 mV underthreshold, ensuring robust operation in noisy power environments.

Key Specifications

Pinout & Package

STM1818SWX7F is housed in a 3-pin SOT23-3 (WX) package - compact, surface-mount, and compatible with standard reflow profiles. Pin 1 is RST (active-low open-drain with internal 5.5 kΩ pull-up and manual reset detect), Pin 2 is VCC (supply input and threshold reference), and Pin 3 is VSS (system ground).

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar reset supervisor applications.

Compared with MAX809TRD2T and TPS3808G01DBVR, STM1818SWX7F uniquely integrates manual reset detection, 4.37 V precision threshold, and 5.5 kΩ pull-up in SOT23-3-enabling minimal-footprint, single-component reset supervision for 3.3 V systems with user-reset capability.

Availability

STM1818SWX7F is available at Aetrix Electronics and suitable for industrial PLC I/O modules, portable medical monitors, automotive body control units, and smart home sensor hubs requiring stable component supply and long-term lifecycle support.

Supply support for STM1818SWX7F includes scheduled delivery planning, volume procurement assistance, BOM continuity management, traceable sourcing, and lifecycle availability coordination for OEM customers, industrial embedded developers, connected-device designers, and electronics production programs.

Manufacturer

STMicroelectronics is a global semiconductor leader headquartered in Geneva, Switzerland, specializing in power management, microcontrollers, and analog ICs for industrial, automotive, and consumer markets.

STM181x is ST's low-power reset supervisor product line, engineered for reliable power monitoring in space-constrained, battery-sensitive, and thermally demanding embedded systems-emphasizing precision thresholding, minimal quiescent current, and integrated manual reset.

FAQ

What is the exact reset threshold voltage for STM1818SWX7F?

The STM1818SWX7F has a factory-trimmed nominal reset threshold of 4.37 V, with ±2.5% accuracy over the full operating temperature range (–40 °C to +105 °C). This value is confirmed in Table 6 and Section 1.2.4 of the official STMicroelectronics datasheet Doc ID11464 Rev 8.

Does STM1818SWX7F require an external pull-up resistor on the RST pin?

No. STM1818SWX7F integrates a 5.5 kΩ internal pull-up resistor to VCC on the RST pin, eliminating the need for an external component. This enables direct connection to bidirectional MCU reset inputs and simplifies PCB layout-verified in Figure 6 and Table 6 of the datasheet.

How does the manual reset detection work on STM1818SWX7F?

The RST pin detects an external low pulse of ≥1.5 µs duration, triggering a full 100 ms reset assertion upon release. Internal debounce circuitry filters mechanical switch bounce, and the feature is exclusive to STM1813/STM1818 variants-documented in Section 2.2 and Figure 9 of the datasheet.

Can STM1818SWX7F operate reliably below 1.0 V VCC?

No. STM1818SWX7F guarantees correct logic state output only down to VCC = 1.0 V (0 °C to +105 °C). Below 1.0 V, the RST output becomes high-impedance. If operation near 0 V is required, a 100 kΩ pull-down resistor is recommended per Figure 11 and Section 2.5 of the datasheet.